Directional antennae



u y 1941. E. KRAMAR ETAL 2,248,762

4 DIRECTIONAL ANTENNAE Filed D60. 17, 1938 fife/riots Ernst ffram arlelma zk 'Jokamzsan funnel) stares P1 nranoTIoNAL ANTENNAE Ernst Kramarand Helmuth Johannson, Berlin,

Germany, assignorsto C. Lorenz Aktiengesellschaft, Berlin-Tempelhof,Germany, a comp'any Application December 17, 1938, Serial No. 246,30

TE e l- I was A .In Germany December 20, 1937 2 Claims. (01.250 41)Directional antennae are known which are composed of individual antennaearranged either to receive or radiate only the vertically polarizedwaves, in order to do away with errors in direction finding. Forsuppressing the horizontal component a number of measures have beenadopted which relate in part to the construction of the individual orcomponent antennae and in part to the use of screenings. The best knownantenna of this kind is the so-called Adcock antenna that comprises fourvertical radiators which are arranged in the angles of a square and arein pairs interconnected crosswise. The operation of these antennasystems resides in the fact that a vertical antenna can receive orradiate such waves only as are vertically polarized, this antenna notresponding to waves polarized horizontally. In order to avoid that thehorizontal lines interconnecting the vertical antennae have a receivingor radiating efiect, whereby a powerful horizontal component wouldresult, these lines in the case of the known arrangements are providedwith a screening or are buried in the ground, in order to increase thescreening efiect.

These antenna systems if properly installed operate to perfection.However, it has been found that in certain cases the desired result isnot attained. Investigations have shown this to be attributable to thefollowing reasons.

A vertical antenna, in order to receive only vertically polarized waves,must be clear of any neighbouring objects. For instance, if such antennais mounted on the ground then it does not respond to the verticalcomponent only but will be sensitive also to horizontally polarizedwaves. This disturbing influence is due to the fact that the electricconstants of the ground are not the same in all directions. Everydissimilarity in the electric conductivity of the ground causes theelectric lines of force to be in part inclined with respect to theearths surface, thus producing an asymmetric distribution of the linesof force. Therefore, the electric behaviour of a vertical antennamounted on non-uniform ground is not the same as if such antenna wereclear of any neighbouring objects or were stood on ideal ground.

In order to compensate for these drawbacks the invention proposes not tomount the antenna system directly on the ground, this usually beingnonuniform, but to arrange it on a plane ground formed of uniformconductive material constituting a large-sized body. Also, in accreasingthe conductivity thereof.

cordance with the invention, the said horizontalinterconnectors areembedded in this ground.

The invention thus provides an artificial ground that consists of ahomogeneous material and which consequently is free from anydissimilarity. The electric lines of force extend at right angles tosuch artificial ground, whereby a symmetric distribution of the lines offorce is obtained. A Vertical antenna erected on such ground is of thesame action as if it were clear of any neighbouring parts. An antennasystem of this kind thus will receive none but vertically polarizedwaves, the horizontal component being completely suppressed. Byembedding the interconnectors in this ground the additional advantage isobtained that these are screened to perfection, also this screeningbeing prevented in this way from radiating or receiving.

It may be mentioned here that wire network or the like has been arrangedas a ground structure. This means, however, has proved not to presentthe required uniformity because these wire structures oxidize andthereby fail to the 01' the same conductivity throughout. Apart fromthis, such wire structures do not constitute a body large enough alwaysto stand the influence of the transmitting oscillations, but are a meansthat may happen to share in these.

The novel antenna arrangement will be of special advantage if arrangedabove a receptacle in which an electrically conducting liquid iscontained. For instance, a reservoir containing water will be suitable,such being the case especially if salts are dissolved in the water, thusin- Since the liquid may be considered a homogeneous or uniform body thesurface of the water will act as a perfectly plane ground incapable ofeffecting field distortions.

One embodiment of the invention is represented in the accompanyingdrawing, in which:

Fig. 1 is a diagrammatic sectional elevation of this embodiment, whileFig. 2 is a diagrammatic plan view thereof.

and therefore need not be considered here. The arrangement is simplestif reservoir l is filled with water or another conductive liquid.

To effect the invention will be still simpler, if the earth below theantenna system is given an equal conductivity throughout. For instance,the earth may be continually impregnated with a liquid, such as water,for example. To such end a tubular system may be arranged below theantenna system, in order to supply the liquid in uniform distribution tothe earth. The well known drainage tubes will be particularly suitablein this connection.

The invention is applicable to all those antenna systems which are toreceive or radiate none but vertically polarized waves. Also there is nolimitation as regards the wave length. It is merely necessary toaccommodate the dimensions of the ground structure to the wave lengthemployed in the respective case. The invention is of special advantagewith short-wave and ultrashort wave systems, as in these cases theartificial ground may be comparatively small.

What is claimed is:

1. A directional antenna system, comprising component antennae, a planeground common to said component antennae comprising homogeneouselectrically conducting material arranged in a pit having lateraldimensions greater than that occupied by said component antennae andsupporting said antennae and having such a depth as to give said grounda large mass to substantially prevent self-oscillation, andinterconnectors for the component antennae, said interconnectors beingembedded in the said homogeneous ground.

2. A directional antenna system, comprising component antennae, a planeground supporting said antennae and comprising a reservoir containing anelectrically conducting liquid.

ERNST KRAMAR. HELMUTH JOHANNSON.

